No need for labels to be polymorphic in ST
No need for labels to be polymorphic in ST

Just use Var - this is what 'new' creates and there's no way they can be
anything else. So use 'Var' specifically, which makes inference easier
elsewhere.

mpkh/Idris-dev,FranklinChen/Idris-dev,uuhan/Idris-dev,kojiromike/Idris-dev,Heather/Idris-dev,Heather/Idris-dev,mpkh/Idris-dev,kojiromike/Idris-dev,markuspf/Idris-dev,markuspf/Idris-dev,uuhan/Idris-dev,Heather/Idris-dev,mpkh/Idris-dev,mpkh/Idris-dev,markuspf/Idris-dev,FranklinChen/Idris-dev,markuspf/Idris-dev,FranklinChen/Idris-dev,uuhan/Idris-dev,kojiromike/Idris-dev,Heather/Idris-dev,kojiromike/Idris-dev,kojiromike/Idris-dev,uuhan/Idris-dev,mpkh/Idris-dev,markuspf/Idris-dev,kojiromike/Idris-dev,mpkh/Idris-dev,uuhan/Idris-dev,Heather/Idris-dev,uuhan/Idris-dev,markuspf/Idris-dev,Heather/Idris-dev,FranklinChen/Idris-dev,uuhan/Idris-dev,FranklinChen/Idris-dev,markuspf/Idris-dev,FranklinChen/Idris-dev